A brushless DC (BLDC) motor is one of the major components of an electro-mechanical actuator (EMA) for aircraft electric braking systems. The motor is used to drive a gear system, which in turn actuates a ball screw assembly that produces the EMA's output force. BLDC motor operation may rely on the availability of a motor shaft position feedback signal to provide the motor controller with necessary angular shaft position information for motor commutation.
Typical technologies used for generating this angular feedback information may include resolvers, optical encoders and magnetic Hall effect sensors. In order to achieve high motor performance and reliability, Hall effect sensors (typically three individual sensor modules arranged under a specific angle) may be adjusted angularly during motor assembly and, after they have been adjusted, permanently potted or overmolded to the motor assembly to resist mechanical shock, vibration, and contamination. As a result, these Hall effect sensors are not individually replaceable in the event of failure and thus the entire motor may be scrapped if a Hall effect sensor fails.